With the advent of gemstone quality synthetic diamonds the need has arisen for a rapid screening system available and affordable for the local jeweler to establish with reasonable probability whether a given diamond gemstone is natural or synthetic.
Existing systems for detection of synthetic diamond gemstones are summarized in the article Shigley et al., "Sumitomo Synthetic Diamonds", Gems and Gemology, Winter 1986, pages 192-208. As there indicated the various properties of diamonds and particularly those that distinguish natural from synthetic stones are compared. Testing procedures were set forth which included color, (which may involve spectroscopy examination), fluorescence, electrical conductivity, thermal conductivity, specific gravity, microscope inspection, reaction to polarized light, and magnetism. As to the latter, magnetism, the test procedure involved gross attraction of the tested diamond to a magnet. However, it was found that only one of the tested synthetic diamonds was attracted so that the reliability of a test as there proposed was found inadequate.
A subsequently published article by Shigley et. al., "Gemological Properties of the De Beers Gem Quality Synthetic Diamonds", Gems and Gemology, Winter 1987, pages 187-206, repeated the previous work and investigation as applied to the De Beers synthetic diamond product. In addition to the tests earlier performed, the last publication also indicates that a test was conducted with catholuminescence and specific gravity investigations as well as chemical analysis of inclusions. As to the magnetic behavior it was noted that natural diamonds are only weakly magnetic if at all and that synthetic diamonds were believed to vary from strongly magnetic to non-magnetic. Accordingly, these studies concluded that magnetic investigation of synthetic diamond gemstones was not useful for identification. They further state that they foresaw difficulties in separating natural from synthetic colorless diamonds using any other conventional gemological technique.
In addition, various techniques have been used to determine the content of magnetic compounds such as magnetite and pyrhotite in ore samples. For example, U.S. Pat. No. 3,808,524 (Tarassoff et al., "APPARATUS FOR DETERMINING THE AMOUNT OF MAGNETIC MATERIAL IN A SAMPLE") discloses an apparatus that determines the amount of a magnetic compound in an ore sample by inserting the sample into a coil of an oscillator and detecting the change in the oscillating frequency of the oscillator.
Conventional teachings in the synthetic diamond art indicate that synthetic diamond screening tests based on magnetic qualities of the diamonds are inadequate. Thus, these teachings suggest that methods such as those disclosed in Tarassoff would probably be ineffective. Accordingly, a need exists for a relatively easy to use and inexpensive method and apparatus for distinguishing between synthetic diamonds and natural diamonds.